Here is a sample from walk-through.
Now I have some questions.
1, I have removed the App tag but it causes a blank display, so what does this App mean?
2, I have noticed some tags begin with upper case and some are not. I think the ones with upper case are controls in UI5 and the other ones are HTML tags, am I right?
3, I found that the tags where can customizing CSS be used are all ones that begin with upper case, is it a rule?